**2. Sugarcane bagasse-based sorbents for motor oil removal**

of drinking water. Besides, dyes cannot be removed by conventional treatment methods, and are resistant to aerobic digestion. As an alternative method, physical removal of dyes from effluent through biosorption has been extensively studied [8, 21]. A dye molecule is characterized by the presence of chromophore groups, which are responsible for producing the color, and also by groups known as auxochromes such as carboxylic acid, sulfonic acid, amino, and hydroxyl groups. These auxochromes are responsible for impacting or shifting of a particular color when attached to a chromophore, and also used to influence the dye solubility. In fact,

**Dyes SB/modification Sorption capacity (mg g−1) References**

Methylene blue Maleic anhydride 30.4 [25] Rhodamine B Without modification 51.3 [2]

Acid Alizarin Violet N Without modification 20.8 [26] Methyl red Phosphoric acid 11.0 [21] Without modification 5.7 Congo red Without modification 39.8 [24] Methylene blue Ethylenediaminetetraacetic dianhydride 115.3 [27] Crystal violet Meldrum's acid 552.7 [7] Methylene blue Ethylenediaminetetraacetic dianhydride 192.3 [19]

Methylene blue Succinic anhydride 434.3 [16]

Erythrosin B Without modification 333.3 [22]


PO4

Auramine O 571.8

**Figure 2.** Example of cationic (erythrosin B) and anionic (methylene blue) dyes.

Methylene blue 28.0

Gentian violet 357.1

Gentian violet 1133.7

Methylene blue 1000.0

Crystal violet Oxidation with H3

268 Sugarcane - Technology and Research

**Table 2.** Examples of dyes adsorption by SB.

Research involving oil sorbents was firstly encouraged by the great environmental accidents generated by oil spills at sea [28–30]. In these cases, the adsorption processes are more suitable to remove and recover the oil. The sorbent material facilitates a transformation from liquid to solid phase, and then oil can be removed together with the sorbent. The main characteristic of crude oil sorbent material is the hydrophobicity and oleophilicity in order to attract oil preferentially to water. However, the amount of sorbents added to an oil polluted environment is a critical factor, because the inappropriate and excessive use can present subsequent waste disposal problems. It is especially important when organic synthetic products are used as sorbents. Synthetic sorbents, as polypropylene, do not degrade and are very expensive. Therefore, agricultural waste by-products were firstly used as an alternative oil sorbent to replace the conventional and nondegradable sorbent used to clean up oil spills. These biosorbents are biodegradable, renewable, abundant, and low cost. Teas et al. [31] compared the oil sorption capacity of cellulose with the expanded perlite and polypropylene in artificial seawater containing crude oil. These authors observed that for crude oil, the sorption capacity of cellulose overtakes the other sorbents. When light cycle oil and light gas oil were used in artificial seawater, they observed lower sorption by cellulose in relation to polypropylene, but similar behavior to expand perlite. The oil sorption capacity of vegetal fibers observed by several authors has been attributed to the interaction with hydrophobic sites in the biomass. Lignocellulosic fibers contain both hydrophilic and hydrophobic groups; however, the cellulose structure has hydrophilic nature with excellent wettability. The chemical functionalization of cellulose can increase its hydrophobic character, which is possible by changing the hydrophilic groups, hydroxyl (−OH) in the raw coir cellulose to hydrophobic hydrocarbons [32–34]. The biomass acetylation has been extensively used to increase its oil sorption capacity. Sun et al. [35] observed that SB acetylated presents greater machine oil sorption capacity (13.5–20.2 g g<sup>−</sup> 1) than polypropylene fibers (10 g g−1). **Table 3** summarizes other studies that have been demonstrated the potential sorbent of agricultural by-products to oil removal and the effect of biomass modification in the sorption capacity.


and a nonuniform product may be obtained [32, 35, 38, 45]. In the case of SB, the acetylation with acetic anhydride should introduce the methyl group and increase hydrophobicity at surface. Other acylating agents such as maleic [46], phthalic [9], and succinic [16] anhydrides have been used to introduce carboxylic groups on fibers and increase its surface

Sugarcane Bagasse As Potentially Low-Cost Biosorbent http://dx.doi.org/10.5772/intechopen.72153 271

Another class of coupling agents recognized as efficient to promote the fiber hydrophobicity or hydrophilicity are the silanes. They have been extensively used to modify the surface of natural fibers to produce composites with thermoplastics or thermosets [47]. The aminosilanes, as the aminopropyltriethoxysilane (APS), are the most reported coupling agents for natural fibers. Recently, APS was successful used to modify the SB surface in order to improve

Despite the great demand for treatment of effluents containing used oil, there is a scarcity of literature on this problem. In this study, this subject is explored in order to verify the potential of SB fibers for oil wastewater treatment. The effect of several coupling agents over SB capacity for sorption of used motor oil is investigated as well as the influence of surfactant in this

Acetic anhydride (99%), maleic anhydride (96%), phthalic anhydride (99%), succinic anhydride (97%), and aminopropyltriethoxysilane (APS) (97%) were purchased from Sigma-Aldrich and used without further purification. The other analytical grade reagents were obtained from Merck (Brazil) and were used as received. The used motor oil used in this study was obtained from Retifica del Rei (São João del Rei, MG, Brazil). SB was supplied by Cachaça Coqueiro (Nazareno, MG, Brazil). The bagasse was washed repeatedly with distilled water to remove all the dirt particles. The washed fiber was then dried in an oven (Q314M, Quimis) at 60°C for 24 h under a flow of air. It was subsequently ground and sieved through 30 mesh sieves (TE648, Tecnal). The resulting natural fiber was designated as SBN and was used as the

Thermal treatment of SBN at 200°C for 24 h was performed to obtain the sample SB-200. The SBN acylation was obtained based on previous reports [44]. Briefly, the fiber was firstly soaked in 10% NaOH solution (using a ratio of 1 g/1 mL) at 0°C for 2 h. The bagasse was then washed with Milli-Q water until neutral pH and dried at 60°C for 24 h. Following this procedure, 70 g of the cleaned bagasse was placed in a 1 L round-bottom flask containing 300 mL of acylating agents and 200 mL of acetic acid. The mixture was acidified by adding

the solution was filtered and the product was rinsed first with ethanol and then with water until the pH reached around pH 7.0. After this procedure, the sample was dried at 60°C for

and maintained under agitation for 24 h at 60°C. At the end of this period,

its hydrophilic properties, and increase its oils sorption capacity [44].

hydrophilicity.

process.

**2.1. Methodology**

*2.1.2. Fiber modification*

SO4

1 mL of H2

starting material to produce the modified SB.

*2.1.1. Reagents*

**Table 3.** Examples of oil sorption by biomass.

In spite of crude oil sorption favored by hydrophobic surface, in the case of used motor oil, this behavior is not completely precise. The crude oil and fresh motor oil composition is based on a mixture of hydrocarbons, and hence present affinity for hydrophobic sorbent. However, the composition of used motor oil has been changed through thermal degradation and contamination from generated waste in the engine. This process leads to the formation of lowmolecular weight compounds and oxidation products [43]. Recently, Guilharduci et al. [44] showed that introduction of hydrophilic groups on SB improve the oil sorption from engine washing wastewater. Besides, it was also verified that surfactant present in wastewater affect the motor oil sorption.

The biomass acylation is well established in the literature, and the method is based on the reaction of hydroxyl groups (−OH) of the fiber surface with acyl groups (RCO–). Considering that the reaction with fiber is a heterogeneous reaction, not all hydroxyl groups is esterified,

and a nonuniform product may be obtained [32, 35, 38, 45]. In the case of SB, the acetylation with acetic anhydride should introduce the methyl group and increase hydrophobicity at surface. Other acylating agents such as maleic [46], phthalic [9], and succinic [16] anhydrides have been used to introduce carboxylic groups on fibers and increase its surface hydrophilicity.

Another class of coupling agents recognized as efficient to promote the fiber hydrophobicity or hydrophilicity are the silanes. They have been extensively used to modify the surface of natural fibers to produce composites with thermoplastics or thermosets [47]. The aminosilanes, as the aminopropyltriethoxysilane (APS), are the most reported coupling agents for natural fibers. Recently, APS was successful used to modify the SB surface in order to improve its hydrophilic properties, and increase its oils sorption capacity [44].

Despite the great demand for treatment of effluents containing used oil, there is a scarcity of literature on this problem. In this study, this subject is explored in order to verify the potential of SB fibers for oil wastewater treatment. The effect of several coupling agents over SB capacity for sorption of used motor oil is investigated as well as the influence of surfactant in this process.

### **2.1. Methodology**
